Android项目架构

从功能需求、设计模式、最佳实践出发考虑

MVP模式

数据、显示、控制解耦，mosby，作者blog1，blog2

依赖注入

• 普通数据注入，Dagger
• View注入ButterKnife。

数据存储

• squidb，基于注解，编译期生成DAO类，model类是编译期生成的，而不是定义表结构的类，对复杂SQL语句的支持非常好
• DBFlow，基于注解，编译期生成DAO类，对关系的支持很好
• ActiveAndroid，基于注解，运行时转换
• greenDAO，编译期生成辅助代码
• StorIO，与rx集成，响应式DBHelper框架

网络连接处理

• Retrofit，使用动态代理将java接口转化为REST API
• OkHttp，优化的HTTP client（共享连接，连接池，透明压缩，缓存，重试等），支持web socket协议

异步处理

• 响应式编程（rx，在java7中使用lambda语法：retrolambda），消息的发出者和响应的接收者在同一模块内，局部性、单对单
• 事件处理（EventBus，Otto），全局性事件、一对多比较合适

测试

• 单元测试（我的印象笔记，Robolectric，使得Android代码能够在PC的JVM上运行测试，加快速度）
  • 对rx的单元测试，非官方RxAssertions，官方TestSubscriber
  • AndroidTDD
• 集成测试（我的印象笔记，Espresso）

持续集成

• jenkins-ci，整合代码托管工具，commit、merge request自动触发构建

工具

• 图片加载
  • Fresco，多来源加载、缓存、内存管理（存放在安卓非堆特殊内存区域）、支持多种格式、多种功能（圆角）
  • Glide，多来源加载、缓存、Object pool内存优化、Context生命周期加载优化、ListView、RecyclerView等加载优化
  • Picasso，使用堆内存，格式稍少
• 模块热加载
  • dynamic-load-apk，通过代理实现启动、显示、执行安装时未定义的Activity，Service，实现模块热加载
• 错误统计
  • fabric，提供crash统计、以及twitter集成
• 调试
  • XLog，函数调用追踪，log出参数、返回值、线程、执行时间，支持方法、类的注解；
  • Fresco，chrome查看log，view heriachy，shared pref，db等；
  • LeakCanary，memory leak检测工具；
• 时间
  • ThreeTenBP，JSR310的java 8以前的兼容实现，比安卓的Date类等强大无数倍；
  • ThreeTenABP，安卓的一个包装，init过程性能更好；
• 导航
  • FragmentArgs，Fragment启动时通过Argument传递参数
  • Dart，Activity之间通过Intent传递Extra参数
  • Pocket Knife，Activity的Extra传递参数，SavedInstance做状态保存/恢复
  • Aftermath，A simple, annotation-based Android library for generating onActivityForResult handlers.
• 动效
  • rebound，通过Android系统的property transition，加上各种变换函数，实现模拟物理的动效；
• 设计
  • sketch
  • zeplin

Develop maintainable apps

• Libraries
  选择第三方库时的考虑
  • Documentation: 文档是否全面
  • Repository Check-ins(Stability): 稳定性、是否保持维护
  • Fulfils a Need: 满足项目需求
• Domain design
  • Keep code simple: OO，一个类只负责一件事
  • Use MVC/MVP/MVVM Pattern
  • Functional Test
  • Use the tools: IDE的重构工具很强大
• Code quality
  • Readability matters
  • 工具
    • CheckStyle
    • Lint
    • Findbugs
    • PMD
  • Refactor Gradually
• Testing
  • Unit test: Every single line of code that you write should be tested. Peroid. -- Robert Martin
  • Junit(...) + Mockito
  • Continuous Integration
  • Code coverage

Android Clean Architecture

分层结构

• Entities: These are the business objects of the application.
• Use Cases: These use cases orchestrate the flow of data to and from the entities. Are also called Interactors.
• Interface Adapters: This set of adapters convert data from the format most convenient for the use cases and entities. Presenters and Controllers belong here.
• Frameworks and Drivers: This is where all the details go: UI, tools, frameworks, etc.
• Dependency Rule: source code dependencies can only point inwards and nothing in an inner circle can know anything at all about something in an outer circle.

安卓项目层次结构示例

使用Rx后的层次结构示例

• Presentation layer: UI tests with Espresso 2 and Android Instrumentation.
• Presenter && View test: 针对接口进行单元测试；对UI简单交互结果逻辑的测试（如：Activity跳转，Fragment切换，相关接口调用）；
• Domain layer: JUnit + Mockito since it is a regular Java module.
• Data layer: Migrated test battery to use Robolectric 3 + JUnit + Mockito.

代码组织（包组织）

• Package by layer
• Package by feature
  • Higher Modularity
  • Easier Code Navigation
  • Minimizes Scope

Flux Architecture

• 结构图
  
  • View: Application interface. It create actions in response to user interactions. Activity or Fragment
  • Dispatcher: Central hub through which pass all actions and whose responsibility is to make them arrive to every Store. An event bus.
  • Store: Maintain the state for a particular application domain. They respond to actions according to current state, execute business logic and emit a change event when they are done. This event is used by the view to update its interface. Simple POJOs with two main attributes: Type: a String identifying the type of event; Data: a Map with the payload for this action.
  • More about Stores
    • Stores contain the status of the application and its business logic.
    • Stores react to Actions emitted by the Dispatcher, execute business logic and emit a change event as result.
    • ...

RxFlux

What is all this Clean Architecture jibber-jabber about?

基础

• SOLID
  • Single Responsiblity
  • Open/Closed
  • Liskov Substitution
  • Interface Segregation
  • Dependency Inversion
• Abstraction
  • 面向接口编程
  • 高内聚，低耦合
    • 内聚：单一模块内，各个部分之间的关系
    • 耦合：各个模块之间的关系
• Vertical slicing
  • Horizontal slicing：传统方式，从服务提供方分包，例如DB, Network, ui...
  • Vertical slicing：源自敏捷，根据功能（use case）进行分包，而将与该功能相关的db, network, ui等部分放到同一个模块中